DSpace Collection:http://hdl.handle.net/2117/7010
Tue, 03 Mar 2015 18:59:23 GMT2015-03-03T18:59:23Zwebmaster.bupc@upc.eduUniversitat Politècnica de Catalunya. Servei de Biblioteques i DocumentaciónoStability of nonlinear teleoperators using PD controllers without velocity measurementshttp://hdl.handle.net/2117/22305
Title: Stability of nonlinear teleoperators using PD controllers without velocity measurements
Authors: Nuño, Emmanuel; Basañez Villaluenga, Luis; Lopez Franco, Carlos; Arana Daniel, Nancy
Abstract: This paper presents two Proportional-Derivative (PD) like controllers for nonlinear bilateral teleoperation systems. Compared to previous controllers of this kind, these schemes do not make use of velocity measurements. Under the assumptions that the human operator and the environment define passive maps from velocity to force, both controllers can ensure boundedness of velocities and position error. Moreover, in the case that the human and environment forces are zero, the controllers ensure velocity and position synchronization. Furthermore, the paper also presents a generalization to the case of teleoperation of networks of multiple robots. Simulations and real experiments, comparing the performance on free motion and interacting with a stiff wall, support the performance of the reported schemes. The experiments have been performed using two 3-degree-of-freedom nonlinear manipulators.http://hdl.handle.net/2117/22305Nuño, Emmanuel; Basañez Villaluenga, Luis; Lopez Franco, Carlos; Arana Daniel, NancynoTime-delay, Bilateral teleoperation, Position tracking, Control schemes, Observer, TutorialThis paper presents two Proportional-Derivative (PD) like controllers for nonlinear bilateral teleoperation systems. Compared to previous controllers of this kind, these schemes do not make use of velocity measurements. Under the assumptions that the human operator and the environment define passive maps from velocity to force, both controllers can ensure boundedness of velocities and position error. Moreover, in the case that the human and environment forces are zero, the controllers ensure velocity and position synchronization. Furthermore, the paper also presents a generalization to the case of teleoperation of networks of multiple robots. Simulations and real experiments, comparing the performance on free motion and interacting with a stiff wall, support the performance of the reported schemes. The experiments have been performed using two 3-degree-of-freedom nonlinear manipulators.Planning manipulation movements of a dual-arm system considering obstacle removinghttp://hdl.handle.net/2117/25096
Title: Planning manipulation movements of a dual-arm system considering obstacle removing
Authors: Rodríguez Pacheco, Carlos; Montaño Sarria, Andrés Felipe; Suárez Feijóo, Raúl
Abstract: The paper deals with the problem of planning movements of two hand-arm robotic systems, considering the possibility of using the robot hands to remove potential obstacles in order to obtain a free access to grasp a desired object. The approach is based on a variation of a Probabilistic Road Map that does not rule out the samples implying collisions with removable objects but instead classifies them according to the collided obstacle(s), and allows the search of free paths with the indication of which objects must be removed from the work-space to make the path actually valid; we call it Probabilistic Road Map with Obstacles (PRMwO). The proposed system includes a task assignment system that distributes the task among the robots, using for that purpose a precedence graph built from the results of the PRMwO. The approach has been implemented for a real dual-arm robotic system, and some simulated and real running examples are presented in the paper. (C) 2014 Elsevier B.V. All rights reserved.http://hdl.handle.net/2117/25096Rodríguez Pacheco, Carlos; Montaño Sarria, Andrés Felipe; Suárez Feijóo, RaúlnoMotion planning, Task planning, Grasping, Dual-arm, ManipulationThe paper deals with the problem of planning movements of two hand-arm robotic systems, considering the possibility of using the robot hands to remove potential obstacles in order to obtain a free access to grasp a desired object. The approach is based on a variation of a Probabilistic Road Map that does not rule out the samples implying collisions with removable objects but instead classifies them according to the collided obstacle(s), and allows the search of free paths with the indication of which objects must be removed from the work-space to make the path actually valid; we call it Probabilistic Road Map with Obstacles (PRMwO). The proposed system includes a task assignment system that distributes the task among the robots, using for that purpose a precedence graph built from the results of the PRMwO. The approach has been implemented for a real dual-arm robotic system, and some simulated and real running examples are presented in the paper. (C) 2014 Elsevier B.V. All rights reserved.Control of teleoperators with joint flexibility, uncertain parameters and time-delayshttp://hdl.handle.net/2117/24836
Title: Control of teleoperators with joint flexibility, uncertain parameters and time-delays
Authors: Nuño, Emmanuel; Sarras, Ioannis; Basañez Villaluenga, Luis; Kinnaert, Michel
Abstract: The problem of controlling a rigid bilateral teleoperator has been the subject of study since the late 1980s and several control approaches have been reported to deal with time-delays, position tracking and transparency. However, the general flexible case is still an open problem. The present paper reports an adaptive and damping injection controller and a proportional plus damping injection (P +d) controller which are capable of globally stabilizing a nonlinear bilateral teleoperator with joint flexibility and time-delays. More precisely, the adaptive scheme is able to cope with uncertainty in the parameters and constant timedelays, while the P + d scheme is shown to treat variable time-delays. In both cases, the teleoperator is composed of a rigid local manipulator and a flexible joint remote manipulator. The extension to the case where the local and remote manipulators exhibit joint flexibility is also reported using the P +d scheme. Under the common assumption that the human operator and the environment are passive it is proven, for the P +d schemes, that the joint and actuator velocities as well as the local and remote position errors are bounded. Moreover, if the human operator and remote environment forces are zero then, for both controllers, position tracking is established and local and remote velocities asymptotically converge to zero. Simulations and experiments are presented to depict the performance of the proposed schemes.Tue, 25 Nov 2014 11:51:55 GMThttp://hdl.handle.net/2117/248362014-11-25T11:51:55ZNuño, Emmanuel; Sarras, Ioannis; Basañez Villaluenga, Luis; Kinnaert, MichelnoBilateral teleoperation, Joint flexibility, Time-delays, Uncertain parametersThe problem of controlling a rigid bilateral teleoperator has been the subject of study since the late 1980s and several control approaches have been reported to deal with time-delays, position tracking and transparency. However, the general flexible case is still an open problem. The present paper reports an adaptive and damping injection controller and a proportional plus damping injection (P +d) controller which are capable of globally stabilizing a nonlinear bilateral teleoperator with joint flexibility and time-delays. More precisely, the adaptive scheme is able to cope with uncertainty in the parameters and constant timedelays, while the P + d scheme is shown to treat variable time-delays. In both cases, the teleoperator is composed of a rigid local manipulator and a flexible joint remote manipulator. The extension to the case where the local and remote manipulators exhibit joint flexibility is also reported using the P +d scheme. Under the common assumption that the human operator and the environment are passive it is proven, for the P +d schemes, that the joint and actuator velocities as well as the local and remote position errors are bounded. Moreover, if the human operator and remote environment forces are zero then, for both controllers, position tracking is established and local and remote velocities asymptotically converge to zero. Simulations and experiments are presented to depict the performance of the proposed schemes.An adaptive controller for nonlinear teleoperators with variable time-delayshttp://hdl.handle.net/2117/24712
Title: An adaptive controller for nonlinear teleoperators with variable time-delays
Authors: Sarras, Ioannis; Nuño, Emmanuel; Basañez Villaluenga, Luis
Abstract: In most real-life bilateral teleoperators the available physical parameters are uncertain and the communications exhibit variable time-delays. In order to confront these situations and only assuming that a bound of the time-delays is known, the present work reports an adaptive controller which ensures asymptotic convergence of both position errors and velocities to zero, provided that a sufficient condition on the control gains is met. Compared to previous related works that only treated constant time-delays, the stability analysis does not rely on the cascade interconnection structure of the local and remote nonlinear dynamics and the linear interconnection map. Instead, the paper employs a different Lyapunov candidate function that incorporates a strictly positive term, the local and remote position error. Some simulations, in free space and interacting with a rigid wall, and experiments, using two nonlinear manipulators, illustrate the performance of the proposed control scheme in the presence of uncertain parameters and variable time-delays. (C) 2014 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.Thu, 13 Nov 2014 10:25:29 GMThttp://hdl.handle.net/2117/247122014-11-13T10:25:29ZSarras, Ioannis; Nuño, Emmanuel; Basañez Villaluenga, LuisnoBILATERAL TELEOPERATION, SYNCHRONIZATION, TRACKING, SYSTEMSIn most real-life bilateral teleoperators the available physical parameters are uncertain and the communications exhibit variable time-delays. In order to confront these situations and only assuming that a bound of the time-delays is known, the present work reports an adaptive controller which ensures asymptotic convergence of both position errors and velocities to zero, provided that a sufficient condition on the control gains is met. Compared to previous related works that only treated constant time-delays, the stability analysis does not rely on the cascade interconnection structure of the local and remote nonlinear dynamics and the linear interconnection map. Instead, the paper employs a different Lyapunov candidate function that incorporates a strictly positive term, the local and remote position error. Some simulations, in free space and interacting with a rigid wall, and experiments, using two nonlinear manipulators, illustrate the performance of the proposed control scheme in the presence of uncertain parameters and variable time-delays. (C) 2014 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.Leader-follower and leaderless consensus in networks of flexible-joint manipulatorshttp://hdl.handle.net/2117/24462
Title: Leader-follower and leaderless consensus in networks of flexible-joint manipulators
Authors: Nuño, Emmanuel; Valle, Daniela; Sarras, Ioannis; Basañez Villaluenga, Luis
Abstract: This work presents some first results on the consensus for networks of nonlinear under-actuated mechanical systems without assuming that the gravity effects are negligible or locally pre-compensated. In particular, the study is focused on networks composed of nonidentical flexible-joint robot manipulators. Through a straightforward Lyapunov stability analysis, it is established that a simple control law provides a solution to the leader-follower consensus problem, provided that at least one follower has a direct access to the leader's position, and to the leaderless consensus problem. The network is modeled as an undirected graph and the network interconnection can have variable time-delays. The proposed controller consists of two different terms, one that dynamically compensates the robot gravity and another which ensures the desired consensus objective. This last term is a simple Proportional plus damping scheme. Simulations, using a network with ten manipulators, and experiments, with three 3 degrees-of-freedom manipulators, are provided to support the theoretical contributions of this work.Fri, 24 Oct 2014 07:47:12 GMThttp://hdl.handle.net/2117/244622014-10-24T07:47:12ZNuño, Emmanuel; Valle, Daniela; Sarras, Ioannis; Basañez Villaluenga, LuisnoNetwork of robots, Flexible arms, Decentralized control, LAGRANGE SYSTEMS, MULTIAGENT SYSTEMS, SWITCHING TOPOLOGY, ELASTIC JOINTS, SYNCHRONIZATION, TRACKING, ROBOTS, CONTROLLER, COORDINATION, ALGORITHMSThis work presents some first results on the consensus for networks of nonlinear under-actuated mechanical systems without assuming that the gravity effects are negligible or locally pre-compensated. In particular, the study is focused on networks composed of nonidentical flexible-joint robot manipulators. Through a straightforward Lyapunov stability analysis, it is established that a simple control law provides a solution to the leader-follower consensus problem, provided that at least one follower has a direct access to the leader's position, and to the leaderless consensus problem. The network is modeled as an undirected graph and the network interconnection can have variable time-delays. The proposed controller consists of two different terms, one that dynamically compensates the robot gravity and another which ensures the desired consensus objective. This last term is a simple Proportional plus damping scheme. Simulations, using a network with ten manipulators, and experiments, with three 3 degrees-of-freedom manipulators, are provided to support the theoretical contributions of this work.Operational space consensus of multiple heterogeneous robots without velocity measurementshttp://hdl.handle.net/2117/22584
Title: Operational space consensus of multiple heterogeneous robots without velocity measurements
Authors: Aldana López, Carlos Iván; Nuño, Emmanuel; Basañez Villaluenga, Luis; Romero, Eduardo
Abstract: This paper proposes a control algorithm for networks of multiple heterogeneous robot manipulators, which solves the leader follower and the leaderless consensus problems in the operational space. In the leader-follower scenario, the controller ensures that all the robots in the network asymptotically reach a given leader pose (position and orientation), provided that, at least, one follower robot has access to the leader pose. Without a leader pose, in the leaderless problem, the robots asymptotically reach a pose of consensus. The controller is a simple distributed proportional plus clamping injection (P+d) scheme which does not require velocity measurements. A singularity-free representation, unit quaternions, is used to describe the orientation of each manipulator. The paper presents some simulations, with a network of six 6-Degrees-of-Freedom (DoF) manipulators, and experiments, with a network of three 6-DoF manipulators, to show the effectiveness of the proposed controller. (C) 2013 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.Wed, 09 Apr 2014 13:49:43 GMThttp://hdl.handle.net/2117/225842014-04-09T13:49:43ZAldana López, Carlos Iván; Nuño, Emmanuel; Basañez Villaluenga, Luis; Romero, EduardonoLEADER-FOLLOWING CONSENSUS, EULER-LAGRANGE SYSTEMS, TIME-VARYING DELAYS, MULTIAGENT SYSTEMS, NONLINEAR TELEOPERATORS, COMMUNICATION DELAYS, TASK-SPACE, SYNCHRONIZATION, COORDINATION, QUATERNIONThis paper proposes a control algorithm for networks of multiple heterogeneous robot manipulators, which solves the leader follower and the leaderless consensus problems in the operational space. In the leader-follower scenario, the controller ensures that all the robots in the network asymptotically reach a given leader pose (position and orientation), provided that, at least, one follower robot has access to the leader pose. Without a leader pose, in the leaderless problem, the robots asymptotically reach a pose of consensus. The controller is a simple distributed proportional plus clamping injection (P+d) scheme which does not require velocity measurements. A singularity-free representation, unit quaternions, is used to describe the orientation of each manipulator. The paper presents some simulations, with a network of six 6-Degrees-of-Freedom (DoF) manipulators, and experiments, with a network of three 6-DoF manipulators, to show the effectiveness of the proposed controller. (C) 2013 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.Coordination of multi-agent Euler-Lagrange systems via energy-shaping: Networking improves robustnesshttp://hdl.handle.net/2117/22313
Title: Coordination of multi-agent Euler-Lagrange systems via energy-shaping: Networking improves robustness
Authors: Nuño, Emmanuel; Ortega, Romeo; Jayawardhana, Bayu; Basañez Villaluenga, Luis
Abstract: In this paper, the robust coordination of multi-agent systems via energy-shaping is studied. The agents are nonidentical, Euler–Lagrange systems with uncertain parameters which are regulated (with and without exchange of information between the agents) by the classical energy-based controller where the potential energy function is shaped such that, if the parameters are known, all agents converge globally to the same desired constant equilibrium. Under parameter uncertainty, the globally asymptotically stable (GAS) equilibrium point is shifted away from its desired value and this paper shows that adding information
exchange between the agents to the decentralized control policy improves the steady-state performance.
More precisely, it proves that if the undirected communication graph is connected, the equilibrium of the networked controller isalways closer (in a suitable metric) to the desired one than that of the decentralized
controller. The result holds for all interconnection gains if the potential energy functions are quadratic, else, it is true for sufficiently large gains. An additional advantage of networking is that the asymptotic stabilization objective can be achieved by using lower gains into the loop. Some experimental results (using two nonlinear manipulators) given support to the main results of the paperThu, 20 Mar 2014 13:22:47 GMThttp://hdl.handle.net/2117/223132014-03-20T13:22:47ZNuño, Emmanuel; Ortega, Romeo; Jayawardhana, Bayu; Basañez Villaluenga, LuisnoPD-controllers, Synchronization, Euler–Lagrange systems, Passivity-based controlIn this paper, the robust coordination of multi-agent systems via energy-shaping is studied. The agents are nonidentical, Euler–Lagrange systems with uncertain parameters which are regulated (with and without exchange of information between the agents) by the classical energy-based controller where the potential energy function is shaped such that, if the parameters are known, all agents converge globally to the same desired constant equilibrium. Under parameter uncertainty, the globally asymptotically stable (GAS) equilibrium point is shifted away from its desired value and this paper shows that adding information
exchange between the agents to the decentralized control policy improves the steady-state performance.
More precisely, it proves that if the undirected communication graph is connected, the equilibrium of the networked controller isalways closer (in a suitable metric) to the desired one than that of the decentralized
controller. The result holds for all interconnection gains if the potential energy functions are quadratic, else, it is true for sufficiently large gains. An additional advantage of networking is that the asymptotic stabilization objective can be achieved by using lower gains into the loop. Some experimental results (using two nonlinear manipulators) given support to the main results of the paperConsensus in networks of nonidentical Euler-Lagrange systems using P plus d controllershttp://hdl.handle.net/2117/22306
Title: Consensus in networks of nonidentical Euler-Lagrange systems using P plus d controllers
Authors: Nuño, Emmanuel; Sarras, Ioannis; Basañez Villaluenga, Luis
Abstract: This paper presents a proportional plus damping controller that can asymptotically drive a network composed of N nonidentical Euler-Lagrange (EL) systems toward a consensus point. The agents can be fully actuated or can belong to a class of underactuated EL-systems. The network is modeled as a weighted and undirected static interconnection graph that can exhibit asymmetric variable time delays. Simulations, using a network with ten EL-systems, are reported to support the theoretical contributions of this study.Thu, 20 Mar 2014 08:07:08 GMThttp://hdl.handle.net/2117/223062014-03-20T08:07:08ZNuño, Emmanuel; Sarras, Ioannis; Basañez Villaluenga, LuisnoConsensus, proportional plus damping (P plus d) controllers, time-delaysThis paper presents a proportional plus damping controller that can asymptotically drive a network composed of N nonidentical Euler-Lagrange (EL) systems toward a consensus point. The agents can be fully actuated or can belong to a class of underactuated EL-systems. The network is modeled as a weighted and undirected static interconnection graph that can exhibit asymmetric variable time delays. Simulations, using a network with ten EL-systems, are reported to support the theoretical contributions of this study.Networking improves robustness in flexible-joint multi-robot systems with only joint position measurementshttp://hdl.handle.net/2117/21167
Title: Networking improves robustness in flexible-joint multi-robot systems with only joint position measurements
Authors: Nuño, Emmanuel; Ortega, Romeo; Jayawardhana, Bayu; Basañez Villaluenga, Luis
Abstract: This paper studies the robustness in the coordination - via energy-shaping - of multiple nonidentical flexible-joint robots with only joint position measurements. The control objective is to drive all manipulators link positions to the same constant equilibrium. If the physical parameters are exactly known, then a classical decentralized energy-shaping controller solves the desired control objective. However, under parameter uncertainty, the globally asymptotically stable equilibrium point is shifted away from the desired value. The main contribution of the paper is to show that the steady-state performance is improved adding to the decentralized control policy information exchange between the agents. More precisely, it is proven that the equilibrium with the networked controller is always closer (in a suitable metric) to the desired one than that using the decentralized controller, provided the communication graph representing the network is undirected and connected. This result holds globally for sufficiently large interconnection gains and locally (in a suitably defined sense) for all values of the gains. An additional advantage of networking is that the asymptotic stabilization objective can be achieved injecting lower gains into the loop. The paper also provides simulation and experimental evidence, which illustrate the fact that networking improves robustness with respect to parameter uncertainty.Wed, 08 Jan 2014 14:14:16 GMThttp://hdl.handle.net/2117/211672014-01-08T14:14:16ZNuño, Emmanuel; Ortega, Romeo; Jayawardhana, Bayu; Basañez Villaluenga, LuisnoThis paper studies the robustness in the coordination - via energy-shaping - of multiple nonidentical flexible-joint robots with only joint position measurements. The control objective is to drive all manipulators link positions to the same constant equilibrium. If the physical parameters are exactly known, then a classical decentralized energy-shaping controller solves the desired control objective. However, under parameter uncertainty, the globally asymptotically stable equilibrium point is shifted away from the desired value. The main contribution of the paper is to show that the steady-state performance is improved adding to the decentralized control policy information exchange between the agents. More precisely, it is proven that the equilibrium with the networked controller is always closer (in a suitable metric) to the desired one than that using the decentralized controller, provided the communication graph representing the network is undirected and connected. This result holds globally for sufficiently large interconnection gains and locally (in a suitably defined sense) for all values of the gains. An additional advantage of networking is that the asymptotic stabilization objective can be achieved injecting lower gains into the loop. The paper also provides simulation and experimental evidence, which illustrate the fact that networking improves robustness with respect to parameter uncertainty.A three-stage method for the 3D reconstruction of the tracheobronchial tree from CT scanshttp://hdl.handle.net/2117/20706
Title: A three-stage method for the 3D reconstruction of the tracheobronchial tree from CT scans
Authors: Rosell Gratacòs, Jan; Cabras, Paolo
Abstract: This paper proposes a method for segmenting the airways from CT scans of the chest to obtain a 3D modelthat can be used in the virtual bronchoscopy for the exploration and the planning of paths to the lesions.The method is composed of 3 stages: a gross segmentation that reconstructs the main airway tree usingadaptive region growing, a finer segmentation that identifies any potential airway region based on a 2Dprocess that enhances bronchi walls using local information, and a final process to connect any isolatedbronchus to the main airways using a morphologic reconstruction process and a path planning technique.The paper includes two examples for the evaluation and discussion of the proposal.Mon, 25 Nov 2013 09:37:44 GMThttp://hdl.handle.net/2117/207062013-11-25T09:37:44ZRosell Gratacòs, Jan; Cabras, PaolonoThis paper proposes a method for segmenting the airways from CT scans of the chest to obtain a 3D modelthat can be used in the virtual bronchoscopy for the exploration and the planning of paths to the lesions.The method is composed of 3 stages: a gross segmentation that reconstructs the main airway tree usingadaptive region growing, a finer segmentation that identifies any potential airway region based on a 2Dprocess that enhances bronchi walls using local information, and a final process to connect any isolatedbronchus to the main airways using a morphologic reconstruction process and a path planning technique.The paper includes two examples for the evaluation and discussion of the proposal.Modeling non-linear viscoelastic behavior under large deformationshttp://hdl.handle.net/2117/20367
Title: Modeling non-linear viscoelastic behavior under large deformations
Authors: del Castillo Pérez, Esteban; Basañez Villaluenga, Luis; Gil Dolcet, Ernest
Abstract: This paper addresses the accurate modeling of the behavior of a thin layer of natural rubber subjected to large deformations. Such a system presents a non-linear viscoelastic behavior similar to many biological soft tissues. The proposed model uses an spring-mass system, and considers a non-linear evolution of the reaction forces of the membrane,as well as viscous and Coulomb friction. In the model, the elasticity
coefficient of the springs has an exponential dependence of its elongation. Three experimental tests validate the proposed model, which reaches a real-time performance using an implicit integratorMon, 14 Oct 2013 07:02:59 GMThttp://hdl.handle.net/2117/203672013-10-14T07:02:59Zdel Castillo Pérez, Esteban; Basañez Villaluenga, Luis; Gil Dolcet, ErnestnoDeformable models, Exponential spring-mass model, Circular membrane, Soft tissueThis paper addresses the accurate modeling of the behavior of a thin layer of natural rubber subjected to large deformations. Such a system presents a non-linear viscoelastic behavior similar to many biological soft tissues. The proposed model uses an spring-mass system, and considers a non-linear evolution of the reaction forces of the membrane,as well as viscous and Coulomb friction. In the model, the elasticity
coefficient of the springs has an exponential dependence of its elongation. Three experimental tests validate the proposed model, which reaches a real-time performance using an implicit integratorPath planning for grasping operations using an adaptive PCA-based sampling methodhttp://hdl.handle.net/2117/20339
Title: Path planning for grasping operations using an adaptive PCA-based sampling method
Authors: Rosell Gratacòs, Jan; Suárez Feijóo, Raúl; Pérez Ruiz, Alexander
Abstract: The planning of collision-free paths for a handarm
robotic system is a difficult issue due to the large number
of degrees of freedom involved and the cluttered environment
usually encountered near grasping configurations. To cope
with this problem, this paper presents a novel importance
sampling method based on the use of principal component
analysis (PCA) to enlarge the probability of finding collisionfree
samples in these difficult regions of the configuration
space with low clearance. By using collision-free samples
near the goal, PCA is periodically applied in order to obtain
a sampling volume near the goal that better covers the free
space, improving the efficiency of sampling-based path planning
methods. The approach has been tested with success on
a hand-arm robotic system composed of a four-finger anthropomorphic
mechanical hand (17 joints with 13 independent
degrees of freedom) and an industrial robot (6 independent
degrees of freedom).Wed, 09 Oct 2013 07:26:14 GMThttp://hdl.handle.net/2117/203392013-10-09T07:26:14ZRosell Gratacòs, Jan; Suárez Feijóo, Raúl; Pérez Ruiz, AlexandernoAnthropomorphic hands, Grasping, Importance sampling, Motion planning, Principal component analysisThe planning of collision-free paths for a handarm
robotic system is a difficult issue due to the large number
of degrees of freedom involved and the cluttered environment
usually encountered near grasping configurations. To cope
with this problem, this paper presents a novel importance
sampling method based on the use of principal component
analysis (PCA) to enlarge the probability of finding collisionfree
samples in these difficult regions of the configuration
space with low clearance. By using collision-free samples
near the goal, PCA is periodically applied in order to obtain
a sampling volume near the goal that better covers the free
space, improving the efficiency of sampling-based path planning
methods. The approach has been tested with success on
a hand-arm robotic system composed of a four-finger anthropomorphic
mechanical hand (17 joints with 13 independent
degrees of freedom) and an industrial robot (6 independent
degrees of freedom).Grasp optimization under specific contact constraintshttp://hdl.handle.net/2117/20245
Title: Grasp optimization under specific contact constraints
Authors: Rosales Gallegos, Carlos; Porta Pleite, Josep Maria; Ros Giralt, Lluís
Abstract: This paper presents a procedure to synthesize highquality grasps for objects that need to be held and manipulated
in a specific way, characterized by a pre-specified set of contact constraints to be satisfied. Due to the multi-modal nature of typical grasp quality measures, approaches that resort to local optimization methods are likely to get trapped into local extrema on such problem. An additional difficulty of the problem is that the set of feasible grasps is a highly-dimensional manifold, implicitly defined by a system of non-linear equations. The proposed procedure finds a way around these issues by focusing
the exploration on a relevant subset of grasps of lower dimension, and tracing this subset exhaustively using a higher-dimensional continuation technique. A detailed atlas of the subset is obtained
as a result, on which the highest-quality grasp according to any desired criterion, or a combination of criteria, can be readily
identified. Examples are included that illustrate the application of the method to a three-fingered planar hand and to the Schunk anthropomorphic hand grasping several objects, using several quality indices.Tue, 01 Oct 2013 12:53:01 GMThttp://hdl.handle.net/2117/202452013-10-01T12:53:01ZRosales Gallegos, Carlos; Porta Pleite, Josep Maria; Ros Giralt, Lluísnorobots
PARAULES AUTOR: anthropomorphic hand, contact constraint, grasp planning, grasp quality index, grasp synthesis, precision graspThis paper presents a procedure to synthesize highquality grasps for objects that need to be held and manipulated
in a specific way, characterized by a pre-specified set of contact constraints to be satisfied. Due to the multi-modal nature of typical grasp quality measures, approaches that resort to local optimization methods are likely to get trapped into local extrema on such problem. An additional difficulty of the problem is that the set of feasible grasps is a highly-dimensional manifold, implicitly defined by a system of non-linear equations. The proposed procedure finds a way around these issues by focusing
the exploration on a relevant subset of grasps of lower dimension, and tracing this subset exhaustively using a higher-dimensional continuation technique. A detailed atlas of the subset is obtained
as a result, on which the highest-quality grasp according to any desired criterion, or a combination of criteria, can be readily
identified. Examples are included that illustrate the application of the method to a three-fingered planar hand and to the Schunk anthropomorphic hand grasping several objects, using several quality indices.Valoración del daño corporal en personas afectadas de secuelas neurológicashttp://hdl.handle.net/2117/18505
Title: Valoración del daño corporal en personas afectadas de secuelas neurológicas
Authors: Peña Pitarch, Esteve; Ticó Falguera, Neus
Abstract: Objetivo: Mostrar un nuevo sistema para simular la recuperación inicial de las funciones de la extremidad superior los primeros días después del ictus y simular la recuperación funcional de los pacientes bajo los programas de rehabilitación.
Pacientes y metodología: Seleccionamos 29 pacientes en los primeros cuatro días después de padecer un ictus,
valorados a los tres y siete días y uno, tres y seis meses, recogiendo tipo de ictus, clasificación (escala de Oxford), déficit neurológico (escala de NIHSS), medidas de discapacidad, valoración de la función motora de la
extremidad superior (escala de Fugl-Meyer), tono muscular y balance muscular de la extremidad superior.
Resultados: Los pacientes que presentaron un tono muscular disminuido tuvieron más dificultad en mejorar el
control motor de las articulaciones de la extremidad superior. Los pacientes TACI presentaron mayor déficit
neurológico, mientras que los tipos de ictus POCI y LACI tenían una función motora mejor con mayor independencia para el desarrollo de sus actividades de la vida diaria.
Conclusión: La simulación virtual del brazo y la mano en pacientes afectados por un ictus proporciona a los
médicos y fisioterapeutas una nueva herramienta que permite simular la evolución de los déficits en algunos
pacientes.Fri, 22 Mar 2013 16:16:33 GMThttp://hdl.handle.net/2117/185052013-03-22T16:16:33ZPeña Pitarch, Esteve; Ticó Falguera, NeusnoObjetivo: Mostrar un nuevo sistema para simular la recuperación inicial de las funciones de la extremidad superior los primeros días después del ictus y simular la recuperación funcional de los pacientes bajo los programas de rehabilitación.
Pacientes y metodología: Seleccionamos 29 pacientes en los primeros cuatro días después de padecer un ictus,
valorados a los tres y siete días y uno, tres y seis meses, recogiendo tipo de ictus, clasificación (escala de Oxford), déficit neurológico (escala de NIHSS), medidas de discapacidad, valoración de la función motora de la
extremidad superior (escala de Fugl-Meyer), tono muscular y balance muscular de la extremidad superior.
Resultados: Los pacientes que presentaron un tono muscular disminuido tuvieron más dificultad en mejorar el
control motor de las articulaciones de la extremidad superior. Los pacientes TACI presentaron mayor déficit
neurológico, mientras que los tipos de ictus POCI y LACI tenían una función motora mejor con mayor independencia para el desarrollo de sus actividades de la vida diaria.
Conclusión: La simulación virtual del brazo y la mano en pacientes afectados por un ictus proporciona a los
médicos y fisioterapeutas una nueva herramienta que permite simular la evolución de los déficits en algunos
pacientes.Hybrid mapping for the assistance of teleoperated grasping taskshttp://hdl.handle.net/2117/17845
Title: Hybrid mapping for the assistance of teleoperated grasping tasks
Authors: Colasanto, Luca; Suárez Feijóo, Raúl; Rosell Gratacòs, Jan
Abstract: Teleoperating a robotic hand with the aid of a sensorized
glove presents some particular problems. A certain problem
is due to the kinematic differences between the human hand
and the robotic hand, which do not allow a simple direct mapping
of the sensor readings from the glove to the robotic hand. This
problem is addressed with different types of mapping, but none
of them is of general use. This paper proposes two new mappings
within two existing mapping types, as well as a new hybrid mapping
that combines the best features of these existing mapping
types. This hybrid mapping allows intuitive free space movements
(where the gesture is more important than the precise positions of
the fingers) and grasp movements (where the precise positions of
the fingers is more important than the gesture), despite kinematic
differences between the human hand and the robotic hand. The
approach has been implemented, and some illustrative examples
are presented in this paper.Mon, 18 Feb 2013 14:58:29 GMThttp://hdl.handle.net/2117/178452013-02-18T14:58:29ZColasanto, Luca; Suárez Feijóo, Raúl; Rosell Gratacòs, JannoTeleoperating a robotic hand with the aid of a sensorized
glove presents some particular problems. A certain problem
is due to the kinematic differences between the human hand
and the robotic hand, which do not allow a simple direct mapping
of the sensor readings from the glove to the robotic hand. This
problem is addressed with different types of mapping, but none
of them is of general use. This paper proposes two new mappings
within two existing mapping types, as well as a new hybrid mapping
that combines the best features of these existing mapping
types. This hybrid mapping allows intuitive free space movements
(where the gesture is more important than the precise positions of
the fingers) and grasp movements (where the precise positions of
the fingers is more important than the gesture), despite kinematic
differences between the human hand and the robotic hand. The
approach has been implemented, and some illustrative examples
are presented in this paper.